A married religious education teacher was quizzed by police over claims she had an inappropriate relationship with a 17-year-old pupil.
Charges were brought against Lynsey Craw, 33, following complaints but proceedings against her were later dropped by the Crown.
Craw is believed to have been suspended from the Glenrothes secondary school where she worked during the probe but it is unclear whether she is still employed by Fife Council.
The allegations involving the schoolgirl first surfaced in May last year but have only just been made public.
Craw, from Tillicoutry in Clackmannanshire, has since separated from her husband.
The police are said to have been called after the teenage pupil involved spoke to her parents about the allegations.
The teacher is believed to have been absent from her post for several months but the local authority would not confirm whether she was still employed at the school.
A council spokesperson said: “We cannot discuss individual circumstances of any employee, either current or former.”
Police Scotland confirmed the investigation, adding: “We investigated a report of inappropriate behaviour received in May 2018.
“A 33-year-old woman was charged in connection with this and a report was submitted to the procurator fiscal in August.”
A Crown Office spokesman said: “After consideration of the facts and circumstances and all the available admissible evidence, Crown counsel instructed that there should be no proceedings at this time.”